This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Asthma is caused by the interaction of genetic and environmental factors. In the U.S., asthma prevalence, morbidity and mortality are highest in Puerto Ricans, intermediate in Dominicans and Cubans, and lowest in Mexicans and Central Americans. Latinos are admixed and share varying proportions of African, Native American and European ancestry. The mixed ancestry of Latinos provides unique opportunities in epidemiological and genetic studies of complex traits and may be useful in untangling complex gene-environment (G x E) interactions in disease susceptibility. We will collect a well-characterized sample of Latino individuals with asthma (n = 2000) and clinic-based controls (n = 2000), age 8-21 years, from the Bronx, NY, Chicago, IL, San Francisco, CA, Houston, TX, and Puerto Rico 1) Test the hypothesis that genetic ancestry interacts with environmental/demographic risk factors to modify asthma risk and asthma-related phenotypes. 2) Genotype fifty candidate genes that may be involved in G x E interactions relevant to asthma. 3) Determine whether migration and acculturation are associated with asthma and severe asthma. Case control study with the objective of collecting a well-characterized sample of Latino asthmatics (n = 2000) and clinic-based controls (n = 2000), age 8-21 years, from the Bronx, NY, Chicago, IL, San Francisco, CA, Houston, TX and Puerto Rico. The Houston site will be responsible for recruiting and enrolling 400 cases and 400 control subjects over a 3 year period. The genetics laboratory will be at University of California, San Francisco We will collect a well-characterized sample of Latino individuals with asthma (n = 2000) and clinic-based controls (n = 2000), age 8-21 years, from the Bronx, NY, Chicago, IL, San Francisco, CA, Houston, TX, and Puerto Rico from which the specific hypotheses described above can be tested. The Houston site will be responsible for recruiting 400 cases and 400 controls over a 3 year period.